selection(n) Tk Built-In Commands selection(n)_________________________________________________________________NAMEselection - Manipulate the X selectionSYNOPSISselection option ?arg arg ...?
_________________________________________________________________DESCRIPTION
This command provides a Tcl interface to the X selection
mechanism and implements the full selection functionality
described in the X Inter-Client Communication Conventions
Manual (ICCCM).
The first argument to selection determines the format of
the rest of the arguments and the behavior of the command.
The following forms are currently supported:
selection clear ?-displayof window? ?-selection selection?
If selection exists anywhere on window's display,
clear it so that no window owns the selection any-
more. Selection specifies the X selection that
should be cleared, and should be an atom name such
as PRIMARY or CLIPBOARD; see the Inter-Client Com-
munication Conventions Manual for complete details.
Selection defaults to PRIMARY and window defaults
to ``.''. Returns an empty string.
selection get ?-displayof window? ?-selection selection?
?-type type?
Retrieves the value of selection from window's dis-
play and returns it as a result. Selection
defaults to PRIMARY and window defaults to ``.''.
Type specifies the form in which the selection is
to be returned (the desired ``target'' for conver-
sion, in ICCCM terminology), and should be an atom
name such as STRING or FILE_NAME; see the Inter-
Client Communication Conventions Manual for com-
plete details. Type defaults to STRING. The
selection owner may choose to return the selection
in any of several different representation formats,
such as STRING, ATOM, INTEGER, etc. (this format is
different than the selection type; see the ICCCM
for all the confusing details). If the selection
is returned in a non-string format, such as INTEGER
or ATOM, the selection command converts it to
string format as a collection of fields separated
by spaces: atoms are converted to their textual
names, and anything else is converted to hexadeci-
mal integers.
Tk 4.0 1
selection(n) Tk Built-In Commands selection(n)selection handle ?-selection selection? ?-type type?
?-format format? window command
Creates a handler for selection requests, such that
command will be executed whenever selection is
owned by window and someone attempts to retrieve it
in the form given by type (e.g. type is specified
in the selection get command). Selection defaults
to PRIMARY, type defaults to STRING, and format
defaults to STRING. If command is an empty string
then any existing handler for window, type, and
selection is removed.
When selection is requested, window is the selec-
tion owner, and type is the requested type, command
will be executed as a Tcl command with two addi-
tional numbers appended to it (with space separa-
tors). The two additional numbers are offset and
maxBytes: offset specifies a starting character
position in the selection and maxBytes gives the
maximum number of bytes to retrieve. The command
should return a value consisting of at most
maxBytes of the selection, starting at position
offset. For very large selections (larger than
maxBytes) the selection will be retrieved using
several invocations of command with increasing off-
set values. If command returns a string whose
length is less than maxBytes, the return value is
assumed to include all of the remainder of the
selection; if the length of command's result is
equal to maxBytes then command will be invoked
again, until it eventually returns a result shorter
than maxBytes. The value of maxBytes will always
be relatively large (thousands of bytes).
If command returns an error then the selection
retrieval is rejected just as if the selection
didn't exist at all.
The format argument specifies the representation
that should be used to transmit the selection to
the requester (the second column of Table 2 of the
ICCCM), and defaults to STRING. If format is
STRING, the selection is transmitted as 8-bit ASCII
characters (i.e. just in the form returned by com-
mand). If format is ATOM, then the return value
from command is divided into fields separated by
white space; each field is converted to its atom
value, and the 32-bit atom value is transmitted
instead of the atom name. For any other format,
the return value from command is divided into
fields separated by white space and each field is
converted to a 32-bit integer; an array of inte-
gers is transmitted to the selection requester.
Tk 4.0 2
selection(n) Tk Built-In Commands selection(n)
The format argument is needed only for compatibil-
ity with selection requesters that don't use Tk.
If Tk is being used to retrieve the selection then
the value is converted back to a string at the
requesting end, so format is irrelevant.
selection own ?-displayof window? ?-selection selection?
selection own ?-command command? ?-selection selection?
window
The first form of selection own returns the path
name of the window in this application that owns
selection on the display containing window, or an
empty string if no window in this application owns
the selection. Selection defaults to PRIMARY and
window defaults to ``.''.
The second form of selection own causes window to become
the new owner of selection on window's display, returning
an empty string as result. The existing owner, if any, is
notified that it has lost the selection. If command is
specified, it is a Tcl script to execute when some other
window claims ownership of the selection away from window.
Selection defaults to PRIMARY.
KEYWORDS
clear, format, handler, ICCCM, own, selection, target,
type
Tk 4.0 3
